PHP Mail() and email marketing

Can i use the php mail() to send mails to over 10000 people ???

will i get noticed and ultimately banned?

This is NOT a snippet, nor is it a PHP question. In regards to PHP itself, yes you can send out how ever many you want so long as you control it to not push you're memory over its maximum usage and you're timeout expiring. PHP won't do anything to stop you.
If your hosted, ask your host if you can use them as a spam server.

thanks for the reply

lets see what the hosting support has to say

Alot of companies would pick you up as spam. If the users have signed up for you to send them emails and you wish to do them all at once just go into google and type in php mail authentication. There will be loads of tutorials on how to authenticate your mail so it won't be classed as spam. However if you send loads and people mark it as spam then yes, you will be banned.

I think you'd be better off using some proper Bulk Mailing software so you can stagger the sending of emails & reduce the chance of being seen as spam.